The present invention relates to automatic circuit breaker detectors.
It is known in prior art automatic circuit breaker detectors to provide a relaxation oscillator transmitter which creates high frequency high amplitude current pulses with a transmitter which plugs into a conventional AC outlet such as in a house wired for 110 AC. The high current amplitude high frequency pulses are transmitted via the 110 AC wiring to a circuit breaker box, located in a designated area within a home or business. Typically the circuit breaker box has a plurality of circuit breaker switches arranged in a column or a row.
Prior art automatic circuit breaker detector receivers are known which emit an audible indication when the receiver unit is brought adjacent to the particular circuit breaker or a line associated with the particular circuit breaker corresponding to the circuit in which the transmitter is plugged at the remote outlet. When the receiver unit begins to emit an audible sound, then the user has identified, without the need for switching off the circuit breaker switch, the particular circuit in which the transmitter has been remotely plugged. This has the known advantage that circuits can be identified without the need of actually switching off the circuit breaker detector. Thus, for example, electronic equipment does not have to be reset after a resumption of power.
It is a significant disadvantage of such prior art automatic circuit breaker detectors that they can provide false indications at the receiver when attempting to locate the circuit breaker corresponding to the remotely plugged in transmitter unit. For example, the receiver unit may emit an audible indication when it is placed adjacent more than one of the circuit breakers in the circuit breaker box, thus providing a false indication. Also, the receiver unit might not provide any indication, despite the presence of the current pulses on the particular circuit which is being located.
It is an object of the present invention to improve the reliability and performance of automatic circuit breaker detectors so as to minimize the presence of false indications, and to maximize sensitivity automatically without manual calibration so that detection of a particular circuit breaker can be reliably detected in most or virtually all instances.
According to the present invention, a method and system are provided for detecting a particular AC circuit from among a plurality of AC circuits at a circuit box. A transmitter is plugged into the particular AC circuit to be detected and which creates a high amplitude high frequency current pulse. With a receiver unit, the particular circuit is sensed at the circuit box by use of a sensing coil. A variable gain stage is employed in conjunction with a threshold comparator and a latch to pick off the signal and latch the signal so that a microprocessor can read the signals and activate an indication to a user when the appropriate circuit has been located. Calibration occurs immediately by decreasing the gain of the variable gain stage automatically until the signal can no longer be detected, and then the gain is increased slightly so that the variable gain stage operates right at a threshold of the threshold comparator.
Also according to the present invention, in the receiver unit a variable gain stage is employed in conjunction with a threshold comparator and a microprocessor and wherein the microprocessor has an interrupt input connected to an output of the threshold comparator so as to pick off the signal so that the microprocessor can read the signals and activate an indication to a user when the appropriate circuit has been located. Calibration occurs immediately by decreasing the gain of the variable stage automatically until the signal can no longer be detected, and then the gain is increased slightly so that the variable gain stage operates right at a threshold of the threshold comparator.